Pharmacokinetic studies will compare the penetration, distribution, and metabolism of optically pure pyrethroid insecticide isomers labeled with carbon-14 in adult male American cockroaches (Periplaneta americana). These studies will determine whether ksy pyrethroid structure-activity relationships observed in bioassays arise from pharmacokinetic selectivity or specificity at the site of action. The possible role of binding to insect hemolymph or mouse blood proteins in the transport of pyrethroids in vivo will be investigated using electrophoresis and quantitative binding assays. The binding of pyrethroids to insect central nervous system and mouse brain homogenates and homogenate subfractions will be examined using optically pure high specific acitivity preparations. Binding will be characterized with respect to stereospecificity, temperature, dissociation kinetics, pH, and inorganic ions; these properties will be evaluated in terms of their consistency with properties expected of a pyrethroid receptor.